1. Field of the Invention:
The present invention relates to a gasoline engine.
More particularly, the present invention relates to a gasoline engine with a single overhead camshaft having duel exhaust cams per cylinder wherein each exhaust cam has duel lobes.
2. Description of the Prior Art:
The gasoline engine is an internal combustion engine. The thermal energy which is released when the gasoline is burned is converted into mechanical energy. In the gasoline engine, the liquid gasoline is mixed with air to form a combustible mixture, which is compressed in the cylinder and finally ignited by an electric spark produced between the electrodes of a sparking plug. The gases which are formed in the cylinder by the combustion of the gasoline and air mixture expand and thrust the piston downwards. Acting through the connecting rod, the piston imparts a rotary motion to the crankshaft. The spent burned gases must then be removed from the cylinder and be replaced by fresh gasoline and air mixture, so that a fresh cycle can begin. The energy needed for effecting this change in the contents of the cylinder is provided by the flywheel, which stores up some of the mechanical energy released by the combustion that takes place in the cylinder. The additional energy developed by the engine can be taken off at the end of the crankshaft.
With internal combustion engines, a distinction is made between four stroke and two stroke operation. To perform a full cycle of operations, the four stroke engine requires four, and the two stroke engine requires two strokes of the piston.
Four Stroke engine
1st stroke: induction stroke: while the inlet valve is open, the descending piston draws fresh gasoline and air mixture into the cylinder.
2nd stroke: compression stroke: While the valves are closed, the rising piston compresses the mixture to a pressure of about 7-8 atm, the mixture is then ignited by the sparking plug.
3rd stroke: power stroke: While the valves are closed, the pressure of the gases of combustion forces the piston downwards.
4th stroke: exhaust stroke: the exhaust valve is open and the rising piston discharges the spent gases from the cylinder.
Since power is developed during one stroke only, the single cylinder four stroke engine has a low degree of uniformity, i.e., the rotation of the crankshaft is subject to considerable accelerations and decelerations during a cycle. More uniform, that is to say, smoother, running is obtained with multi-cylinder engines because the "cranks" of the crankshaft are staggered in relation to one another so that the various cylinders do not develop their power strokes simultaneously, but successively, and sometimes in an overlapping sequence. Depending on the cylinder arrangement, various types of engine, for various types of usage, are available.
In this type of engine, the piston periodically covers and uncovers opening known as ports in the cylinder wall. The two stroke engine is seldom equipped with valves.
At the start of the first stroke, the piston is in its highest position. When the compressed gasoline and air over the piston is ignited, the latter is thrust downwards and, in so doing, releases the exhaust port. The burned gases in the cylinder, which are still under high pressure, can thus escape through this port. When the piston descends further, its upper edge releases the inlet port, which admits fresh gasoline mixture into the cylinder, so that the remaining burned gases are flushed out. When the piston rises again, second stroke, all the ports are closed for a time, and during this period the gasoline and air mixture is compressed, so that a fresh cycle can commence.
The crankcase scavenged two stroke engine has no scavenging fan. Instead, the crankcase is hermetically sealed, so that it can function as a pump in conjunction with the piston. When the piston ascends, a partial vacuum is produced in the crankcase, until the lower edge of the piston releases the inlet port and thus opens the way to the fresh gasoline and air mixture into the crankcase. When the piston descends, the mixture in the crankcase is compressed a little so that, as soon as the top of the piston releases the transfer port and overflow duct connecting the crankcase to the cylinder, it can enter the cylinder. Meanwhile, what happens above the piston is, as above.
In the latter type of two stroke engine the fan adds to the cost. However, as the overflow duct between the cylinder and crankcase is eliminated, the crankshaft is provided with forced oil lubrication without involving a risk that the oil in the crankcase can find its way into the cylinder. In the cheaper crankcase-scavenged engine, the lubricating oil is mixed with the gasoline, or is, alternatively, supplied to the points of lubrication dropwise by small lubricating oil pumps. The oil which enters the crankcase is liable to be carried through the overflow duct and transfer port into the cylinder, whence it passes through the exhaust port and into the exhaust system, where it may manifest itself as blue smoke in the exhaust.
Numerous innovations for gasoline engines have been provided in the prior art that are adapted to be used. Even though these innovations may be suitable for the specific individual purposes to which they address, they would not be suitable for the purposes of the present invention as heretofore described.